Turbine blades of gas turbine engines usually suffer from severe operational conditions characterized by high temperature and stress. Severe operational conditions during service cause microstructural changes in turbi...Turbine blades of gas turbine engines usually suffer from severe operational conditions characterized by high temperature and stress. Severe operational conditions during service cause microstructural changes in turbine blades and degrade their mechanical properties. In this study, service-induced microstructural damages in serviced turbine blades manufactured from a directionally solidified superalloy were evaluated. The observed microstructural damage of the turbine blade mainly involves the coarsening and rafting of γ' precipitates. The leading edge of 60% height of the turbine blades undergone most severe microstructural damage with significant microstructural evolution at this area. Microstructural damage affects the mechanical properties such as Vickers hardness, that is,Vickers hardness decreases as the equivalent diameter decreases. Microstructural damage shows great positiondependent feature as service temperature and radial stress on blade changes. With the aid of energy-dispersive spectrometer(EDS) analysis on carbide, the transformation of carbide does not exist. In addition, no topological closed-packed phase exists in the turbine blade.展开更多
In the background of“double carbon,”vigorously developing new energy is particularly important.Wind power is an important clean energy source.In the field of new energy,wind power scale is also expanding.With the wi...In the background of“double carbon,”vigorously developing new energy is particularly important.Wind power is an important clean energy source.In the field of new energy,wind power scale is also expanding.With the wind turbine,the probability of large-scale blade damage is also increasing.Because the large wind turbine blade crack detection cost is high and because of the poor working environment,this paper proposes a wind turbine blade surface defect detection method based on UAV acquisition images and digital image pro-cessing.The application of weighted averages to achieve grayscale processing,followed by median filtering to achieve image noise reduction,and an improved histogram equalization algorithm is proposed and used for the characteristics of the UAV acquisition images,which enhances the image by limiting the contrast adaptive his-togram equalization algorithm to make the details at the target area and defects more clear and complete,and improves the detection efficiency.The detection of the blade surface is achieved by separating and extracting the feature information from the defects through image foreground segmentation,threshold processing,and framing by the connected domain.The validity and accuracy of the proposed method in leaf detection were verified by experiments.展开更多
A damage assessment methodology based on the Hashin failure theory for glass fiber reinforced polymer(GFRP)composite blade is proposed. The typical failure mechanisms including the fiber tension/compression and matrix...A damage assessment methodology based on the Hashin failure theory for glass fiber reinforced polymer(GFRP)composite blade is proposed. The typical failure mechanisms including the fiber tension/compression and matrix tension/compression are considered to describe the damage behaviors. To give the flapwise and edgewise loading along the blade span, the Blade Element Momentum Theory(BEMT) is adopted. In conjunction with the hydrodynamic analysis, the structural analysis of the composite blade is cooperatively performed with the Hashin damage model. The damage characteristics of the composite blade, under normal and extreme operational conditions,are comparatively analyzed. Numerical results demonstrate that the matrix tension damage is the most significant failure mode which occurs in the mid-span of the blade. The blade internal configurations including the box-beam, Ibeam, left-C beam and right-C beam are compared and analyzed. The GFRP and carbon fiber reinforced polymer(CFRP) are considered and combined. Numerical results show that the I-beam is the best structural type. The structural performance of composite tidal turbine blades could be improved by combining the GFRP and CFRP structure considering the damage and cost-effectiveness synthetically.展开更多
为阐明测试单元环境下加速任务试车(AMT)过程中叶片早期起裂的物理原因,对裂纹叶片断口进行了检查和分析,并采用LPTi s XactLIFETM系统对叶片进行了深入的分析.结果表明:叶片叶型发生了过量的蠕变损伤,此过量的蠕变损伤导致了叶片的过...为阐明测试单元环境下加速任务试车(AMT)过程中叶片早期起裂的物理原因,对裂纹叶片断口进行了检查和分析,并采用LPTi s XactLIFETM系统对叶片进行了深入的分析.结果表明:叶片叶型发生了过量的蠕变损伤,此过量的蠕变损伤导致了叶片的过量延伸以及叶型特别是在尾缘区域的转扭,此行为可能造成AMT疲劳循环条件下缘板以下的叶片伸根部位疲劳裂纹的形核与生长.因此,过量的蠕变被认为是整个裂纹形核过程的主要驱动力.展开更多
基金financially supported by the National Basic Research Program of China (No. 2015CB057401)
文摘Turbine blades of gas turbine engines usually suffer from severe operational conditions characterized by high temperature and stress. Severe operational conditions during service cause microstructural changes in turbine blades and degrade their mechanical properties. In this study, service-induced microstructural damages in serviced turbine blades manufactured from a directionally solidified superalloy were evaluated. The observed microstructural damage of the turbine blade mainly involves the coarsening and rafting of γ' precipitates. The leading edge of 60% height of the turbine blades undergone most severe microstructural damage with significant microstructural evolution at this area. Microstructural damage affects the mechanical properties such as Vickers hardness, that is,Vickers hardness decreases as the equivalent diameter decreases. Microstructural damage shows great positiondependent feature as service temperature and radial stress on blade changes. With the aid of energy-dispersive spectrometer(EDS) analysis on carbide, the transformation of carbide does not exist. In addition, no topological closed-packed phase exists in the turbine blade.
文摘In the background of“double carbon,”vigorously developing new energy is particularly important.Wind power is an important clean energy source.In the field of new energy,wind power scale is also expanding.With the wind turbine,the probability of large-scale blade damage is also increasing.Because the large wind turbine blade crack detection cost is high and because of the poor working environment,this paper proposes a wind turbine blade surface defect detection method based on UAV acquisition images and digital image pro-cessing.The application of weighted averages to achieve grayscale processing,followed by median filtering to achieve image noise reduction,and an improved histogram equalization algorithm is proposed and used for the characteristics of the UAV acquisition images,which enhances the image by limiting the contrast adaptive his-togram equalization algorithm to make the details at the target area and defects more clear and complete,and improves the detection efficiency.The detection of the blade surface is achieved by separating and extracting the feature information from the defects through image foreground segmentation,threshold processing,and framing by the connected domain.The validity and accuracy of the proposed method in leaf detection were verified by experiments.
基金financially supported by the Marine Renewable Energy Research Project of State Oceanic Administration of China(Grant No.GHME2013GC03)
文摘A damage assessment methodology based on the Hashin failure theory for glass fiber reinforced polymer(GFRP)composite blade is proposed. The typical failure mechanisms including the fiber tension/compression and matrix tension/compression are considered to describe the damage behaviors. To give the flapwise and edgewise loading along the blade span, the Blade Element Momentum Theory(BEMT) is adopted. In conjunction with the hydrodynamic analysis, the structural analysis of the composite blade is cooperatively performed with the Hashin damage model. The damage characteristics of the composite blade, under normal and extreme operational conditions,are comparatively analyzed. Numerical results demonstrate that the matrix tension damage is the most significant failure mode which occurs in the mid-span of the blade. The blade internal configurations including the box-beam, Ibeam, left-C beam and right-C beam are compared and analyzed. The GFRP and carbon fiber reinforced polymer(CFRP) are considered and combined. Numerical results show that the I-beam is the best structural type. The structural performance of composite tidal turbine blades could be improved by combining the GFRP and CFRP structure considering the damage and cost-effectiveness synthetically.
文摘为阐明测试单元环境下加速任务试车(AMT)过程中叶片早期起裂的物理原因,对裂纹叶片断口进行了检查和分析,并采用LPTi s XactLIFETM系统对叶片进行了深入的分析.结果表明:叶片叶型发生了过量的蠕变损伤,此过量的蠕变损伤导致了叶片的过量延伸以及叶型特别是在尾缘区域的转扭,此行为可能造成AMT疲劳循环条件下缘板以下的叶片伸根部位疲劳裂纹的形核与生长.因此,过量的蠕变被认为是整个裂纹形核过程的主要驱动力.
